2006 Dodge Charger Engine

I changed the water pump when it went bad. The car overheated and my wife shut the car off she waiting to try and restart it and when she did the engine cranked and made a rattling noise then died. I tried it again and it does the exact same thing. The dodge dealer ship here said that it was only firing on 3 cylinders but they said that because they hooked up the scanner but never actually opened the engine. I know that the engine has aluminum heads so the excessive heat would warp them and valves. I wanted to get your input on what it might be and if im better off with buying a new engine or if I could fix the one already installed.


thank you in advance. Juan gonzalez